J/ApJ/898/150 High-res. MIKE obs. of metal-poor stars (Ezzeddine+, 2020)
The r-process alliance: first Magellan/MIKE release from the Southern search
for r-process-enhanced stars.
Ezzeddine R., Rasmussen K., Frebel A., Chiti A., Hinojisa K., Placco V.M.,
Ji A.P., Beers T.C., Hansen T.T., Roederer I.U., Sakari C.M., Melendez J.
<Astrophys. J., 898, 150 (2020)>
=2020ApJ...898..150E 2020ApJ...898..150E
ADC_Keywords: Stars, metal-deficient; Stars, population II; Infrared sources;
Equivalent widths; Radial velocities; Effective temperatures;
Abundances; Spectra, optical
Keywords: Population II stars ; Chemical abundances ;
Stellar properties ; Stellar types
Abstract:
Extensive progress has recently been made in our understanding of
heavy-element production via the r-process in the universe,
specifically with the first observed neutron star binary merger (NSBM)
event associated with the gravitational-wave signal detected by LIGO,
GW170817. The chemical abundance patterns of metal-poor
r-process-enhanced stars provide key evidence for the dominant site(s)
of the r-process and whether NSBMs are sufficiently frequent or
prolific r-process sources to be responsible for the majority of
r-process material in the universe. We present atmospheric stellar
parameters (using a nonlocal thermodynamic equilibrium analysis) and
abundances from a detailed analysis of 141 metal-poor stars carried
out as part of the R-Process Alliance (RPA) effort. We obtained
high-resolution "snapshot" spectroscopy of the stars using the MIKE
spectrograph on the 6.5m Magellan Clay telescope at Las Campanas
Observatory in Chile. We find 10 new highly enhanced r-II (with
[Eu/Fe]>+1.0), 62 new moderately enhanced r-I (+0.3<[Eu/Fe]≲+1.0),
and 17 new limited-r ([Eu/Fe]<+0.3) stars. Among those, we find 17 new
carbon-enhanced metal-poor (CEMP) stars, of which five are CEMP-no. We
also identify one new s-process-enhanced ([Ba/Eu]>+0.5) and five new
r/s (0.0<[Ba/Eu]<+0.5) stars. In the process, we discover a new
ultra-metal-poor (UMP) star at [Fe/H]=-4.02. One of the r-II stars
shows a deficit in α and Fe-peak elements, typical of dwarf
galaxy stars. Our search for r-process-enhanced stars by RPA efforts
has already roughly doubled the known r-process sample.
Description:
All targets were observed at high spectral resolution using the
Magellan Inamori Kryogenic Echelle (MIKE) spectrograph on the Clay
(Magellan II) telescope at Las Campanas Observatory, Chile. Overall, a
total of 148 stars with visual magnitudes (V) between 10.0 and 14.5
were observed. The spectra were collected over the course of 3yr,
from 2015 January through 2018 December. All spectra cover the
wavelength range from ∼3860 to ∼9000Å with R∼28000 or 22000 in the
red and ∼35000 or 28000 in the blue.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 111 148 Observational details of the target stars
table2.dat 63 45197 Atomic line properties, equivalent widths and
abundances of the target stars
table3.dat 110 141 Stellar atmospheric parameters of the target stars
table4.dat 95 141 Stellar sub-classifications and associated
abundances
table5.dat 122 141 Light-element and α-element abundances
table6.dat 100 141 Fe-peak element abundances
--------------------------------------------------------------------------------
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
III/279 : RAVE 5th data release (Kunder+, 2017)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
J/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)
J/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/A+A/516/A46 : HE 2327-5642 abundance analysis (Mashonkina+, 2010)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/MNRAS/444/392 : Synthetic Stellar Photometry. I. (Casagrande+, 2014)
J/A+A/571/A47 : Extensive linelist of CH in star atmospheres (Masseron+, 2014)
J/ApJ/797/21 : Carbon-enhanced metal-poor stars (Placco+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/ApJ/797/13 : Abundances of bright metal-poor stars (Schlaufman+, 2014)
J/ApJ/830/93 : Abundances of Ret II brightest red giant members (Ji+, 2016)
J/AJ/151/82 : Brightest red giants in the UFD galaxy Ret 2 (Roederer+, 2016)
J/ApJ/847/142 : Ultra-metal-poor stars LTE & NLTE abundances (Ezzeddine+, 2017)
J/ApJ/844/18 : RAVE J203843.2-002333 high-res. spectroscopy (Placco+, 2017)
J/A+A/612/A90 : Inelastic Fe+H collision data (Barklem, 2018)
J/ApJ/864/43 : Abund. of 3 bright extremely metal-poor giants (Cain+, 2018)
J/ApJ/862/174 : Spectroscopy obs. of RAVE J094921.8-161722 (Gull+, 2018)
J/ApJ/858/92 : RPA Southern Pilot Search of 107 Stars (Hansen+, 2018)
J/AJ/155/256 : Spectroscopy of RAVE metal-poor stars (Placco+, 2018)
J/AJ/156/179 : r-process-enhanced field stars kinematics (Roederer+, 2018)
J/ApJ/865/129 : Abundance analysis of HD 222925 (Roederer+, 2018)
J/ApJ/868/110 : R-Process Alliance: 1st release in Gal. halo (Sakari+, 2018)
J/A+A/631/A80 : Mn lines in late-type stars (Bergemann+, 2019)
J/ApJ/870/122 : Spectroscopy of low-metallicity star candidates (Placco+, 2019)
J/ApJ/874/148 : Metal-poor star RAVE J093730.5-062655 abund. (Sakari+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 25 A1 --- f_2MASS Flag on 2MASS (1)
27- 28 I2 h RAh Hour of Right Ascension (J2000)
30- 31 I2 min RAm Minute of Right Ascension (J2000)
33- 38 F6.3 s RAs Second of Right Ascension (J2000)
40- 40 A1 --- DE- Sign of the Declination (J2000)
41- 42 I2 deg DEd Degree of Declination (J2000)
44- 45 I2 arcmin DEm Arcminute of Declination (J2000)
47- 52 F6.3 arcsec DEs Arcsecond of Declination (J2000)
54- 59 F6.3 mag Vmag [10.08/14.17] RAVE DR5 V band magnitude
from RAVE DR5, Kunder+ (2017, III/279)
61- 64 I4 s Exp [240/9265] Exposure time
66- 68 F3.1 arcsec Slit [0.7/1] Slit width
70- 76 F7.1 d MJD [56763.5/58386.5] Modified Julian Date of
observation (JD-2400000.5)
78- 80 I3 --- SN [15/200] Signal-to-noise
82- 88 F7.2 km/s HRVl [-317/473] Literature heliocentric radial velocity
90- 96 F7.2 km/s HRVg [-322/472]? Gaia DR2 heliocentric radial velocity
98-111 A14 --- r_HRVl Source for HRVl (2)
--------------------------------------------------------------------------------
Note (1): Source note as follows:
b = Re-discovery of the ultra-metal-poor (UMP) star CD-38 245.
c = Double-lined spectroscopic binaries (SB2).
Note (2): Metal-poor, candidate r-process-enhanced target stars were selected
from various metal-poor surveys, including the following:
RAVE = the RAdial Velocity Experiment (Steinmetz+ 2006AJ....132.1645S 2006AJ....132.1645S ;
59 occurrences)
SkyMapper = Wolf+ 2018, II/358 ; see also Da Costa+ 2019MNRAS.489.5900D 2019MNRAS.489.5900D
(30 occurrences)
LAMOST = the Large Sky Area Multi-Object Fibre Spectroscopic Telescope
(C. Liu, private communication ; 22 occurrences)
B+B = Best & Brightest (Schlaufman & Casey 2014, J/ApJ/797/13 ;
Placco+ 2019, J/ApJ/870/122 ; 20 occurrences)
M+P = Melendez & Placco (Melendez+ 2016A&A...585L...5M 2016A&A...585L...5M ;
9 occurrences)
HES = The Hamburg/ESO Survey (Christlieb+ 2008, J/A+A/484/721 ;
6 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 32 F8.3 0.1nm lambda [3321.69/8824.3] Wavelength, Angstroms
34- 37 A4 --- Ion Species
39- 42 F4.2 eV ExPot [0/5.06] Excitation potential in eV
44- 49 F6.3 [-] log(gf) [-5.69/0.65] Log oscillator strength
51- 57 F7.2 10-13m EW [0.9/1171] Equivalent width, in mÅ units
59- 63 F5.2 [Sun] logeps(x) [-1/9.3] Log number abundance of Ion
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 28 I4 K TeffLTE [4120/6470] Surface Effective Temperature,
LTE
30- 33 F4.2 [cm/s2] loggLTE [0/4.25] Surface gravity, LTE
35- 38 F4.2 km/s vtLTE [1.1/5.5] Microturbulent velocity, LTE
40- 44 F5.2 [-] [Fe/H]LTE [-4.5/-0.5] Metallicity, LTE
46- 49 I4 K TeffLTEc [4369/6493] Surface Effective Temperature,
LTEcorr
51- 54 F4.2 [cm/s2] loggLTEc [0.3/4.4] Surface gravity, LTEcorr
56- 59 F4.2 km/s vtLTEc [1.2/3.9] Microturbulent velocity,
LTEcorr
61- 65 F5.2 [-] [Fe/H]LTEc [-4.2/-0.3] Metallicity, LTEcorr
67- 70 F4.2 [-] e_[Fe/H]LTEc [0.04/0.3] Uncertainty in [Fe/H], LTEcorr
72- 75 I4 K TeffNLTE [4280/6400] Surface Effective Temperature,
NLTE
77- 80 F4.2 [cm/s2] loggNLTE [1/4.5] Surface gravity, NLTE
82- 85 F4.2 km/s vtNLTE [1.3/3.4] Microturbulent velocity, NLTE
87- 91 F5.2 [-] [Fe/H]NLTE [-4.02/-0.1] Metallicity, NLTE
93- 96 F4.2 [-] e_[Fe/H]NLTE [0.04/0.3] Uncertainty in [Fe/H], NLTE
98-100 I3 --- NFeI [37/268] Number, FeI lines
102-103 I2 --- NFeII [5/63] Number, FeII lines
105-108 F4.2 [cm/s2] loggg [0.6/4.2] Gaia surface gravity
110-110 A1 --- f_loggg Flag on loggg (1)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
a = Uncertain Gaia logg due to Gaia DR2 parallax-based distance
larger than 6kpc Bailer-Jones+ (2018, I/347).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 25 A1 --- f_2MASS Source notes (2)
27- 27 A1 --- l_[C/Fe] Limit flag for [C/Fe]
29- 33 F5.2 [-] [C/Fe] [-3.31/1.7] Carbon to Iron abundance (G1)
35- 35 A1 --- l_[C/Fe]c Limit flag for [C/Fe]c
37- 41 F5.2 [-] [C/Fe]c [-2.72/1.8]? Carbon to Iron abundance,
corrected (G1)(3)
43- 43 A1 --- l_[Sr/Fe] Limit flag for [Sr/Fe]
45- 49 F5.2 [-] [Sr/Fe] [-2.94/1.25] Strontium to Iron abundance (G1)
51- 51 A1 --- l_[Ba/Fe] Limit flag for [Ba/Fe]
53- 57 F5.2 [-] [Ba/Fe] [-2.1/2.5] Barium to Iron abundance (G1)
59- 59 A1 --- l_[Eu/Fe] Limit flag for [Eu/Fe]
61- 65 F5.2 [-] [Eu/Fe] [-0.8/2.2]? Europium to Iron abundance (G1)
67- 67 A1 --- l_[Ba/Eu] Limit flag for [Ba/Eu]
69- 73 F5.2 [-] [Ba/Eu] [-1.85/0.6]? Barium to Europium abundance (G1)
75- 79 F5.2 [-] [Sr/Ba] [-3.4/2.1] Strontium to Barium abundance (G1)
81- 95 A15 --- Sub-class Dominant neutron capture process (4)
--------------------------------------------------------------------------------
Note (2): Source note as follows:
a = Rediscovery of the ultra metal-poor (UMP) star CD-38+245
Note (3): Corrected for evolutionary status following
Placco+ (2014, J/ApJ/797/21).
Note (4): Dominant neutron capture processes, following
Frebel+ (2018ARNPS..68..237F 2018ARNPS..68..237F).
Values with "?" or mixed cases are uncertain.
CEMP-limited-r = [C/Fe]>+0.7 and [Eu/Fe]<+0.3 and [Sr/Ba]>+0.5 and
[Sr/Eu]>0.0;
CEMP-no = [C/Fe]>+0.7 and [Ba/Fe]<0.0;
CEMP-r-I = [C/Fe]>+0.7 and +0.3≤[Eu/Fe]≤+1.0 and [Ba/Eu]<0.0;
CEMP-r-II = [C/Fe]>+0.7 and [Eu/Fe]>+1.0 and [Ba/Eu]<0.0;
CEMP-r/s = [C/Fe]>+0.7 and 0.0<[Ba/Eu]<+0.5;
CEMP-s = [C/Fe]>+0.7 and [Ba/Fe]>+1.0 and [Ba/Eu]>+0.5;
limited-r = [Eu/Fe]<+0.3, [Sr/Ba]>+0.5, and [Sr/Eu]>0.0;
non-RPE = Non-r-process enhanced: [Eu/Fe]<+0.3, [Sr/Ba]≤0.5, and
[Sr/Eu]<0.0;
r-I = +0.3≤[Eu/Fe]≤+1.0 and [Ba/Eu]<0.0;
r-II = [Eu/Fe]>+1.0 and [Ba/Eu]<0.0;
r/s = 0.0<[Ba/Eu]<+0.5.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 29 F5.2 [-] [O/H] [-2.2/0.71]? Oxygen to Hydrogen abundance (G1)
31- 34 F4.2 [-] e_[O/H] [0.02/0.2]? Uncertainty in [O/H]
36- 40 F5.2 [-] [Na/H] [-4.1/-0.08] Sodium to Hydrogen abundance (G1)
42- 45 F4.2 [-] e_[Na/H] [0/0.23] Uncertainty in [Na/H]
47- 51 F5.2 [-] [Mg/H] [-3.6/-0.2] Magnesium to Hydrogen abundance (G1)
53- 56 F4.2 [-] e_[Mg/H] [0.04/0.25] Uncertainty in [Mg/H]
58- 62 F5.2 [-] [Al/H] [/-1.87]? Aluminum to Hydrogen abundance (G1)
64- 67 F4.2 [-] e_[Al/H] [0.15]? Uncertainty in [Al/H]
69- 73 F5.2 [-] [Si/H] [-3.6/-0.09]? Silicon to Hydrogen abundance (G1)
75- 78 F4.2 [-] e_[Si/H] [0/0.27]? Uncertainty in [Si/H]
80- 84 F5.2 [-] [K/H] [-3/-0.02]? Potassium to Hydrogen abundance (G1)
86- 89 F4.2 [-] e_[K/H] [0/0.16]? Uncertainty in [K/H]
91- 95 F5.2 [-] [Ca/H] [-3.7/-0.13] Calcium to Hydrogen abundance (G1)
97-100 F4.2 [-] e_[Ca/H] [0.04/0.32] Uncertainty in [Ca/H]
102-106 F5.2 [-] [TiI/H] [-3.6/-0.4] Titanium I to Hydrogen abundance (G1)
108-111 F4.2 [-] e_[TiI/H] [0/0.28] Uncertainty in [TiI/H]
113-117 F5.2 [-] [TiII/H] [-3.8/0] Titanium II to Hydrogen abundance (G1)
119-122 F4.2 [-] e_[TiII/H] [0/0.32] Uncertainty in [TiII/H]
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- --- [2MASS]
7- 23 A17 --- 2MASS 2MASS name (JHHMMSSss+DDMMSSs)
25- 29 F5.2 [-] [Sc/H] [-3.92/-0.01] Scandium to Hydrogen abundance (G1)
31- 34 F4.2 [-] e_[Sc/H] [0/0.3] Uncertainty in [Sc/H]
36- 40 F5.2 [-] [V/H] [-3.34/0]? Vanadium to Hydrogen abundance (G1)
42- 45 F4.2 [-] e_[V/H] [0/0.3]? Uncertainty in [V/H]
47- 51 F5.2 [-] [Cr/H] [-3.8/-0.19]? Chromium to Hydrogen abundance (G1)
53- 56 F4.2 [-] e_[Cr/H] [0/0.28]? Uncertainty in [Cr/H]
58- 62 F5.2 [-] [Mn/H] [-5.03/-0.12]? Manganese to Hydrogen abundance (G1)
64- 67 F4.2 [-] e_[Mn/H] [0/0.3]? Uncertainty in [Mn/H]
69- 73 F5.2 [-] [Co/H] [-3.7/-0.03]? Cobalt to Hydrogen abundance (G1)
75- 78 F4.2 [-] e_[Co/H] [0/0.3]? Uncertainty in [Co/H]
80- 84 F5.2 [-] [Ni/H] [-4.04/-0.25] Nickel to Hydrogen abundance (G1)
86- 89 F4.2 [-] e_[Ni/H] [0/0.31] Uncertainty in [Ni/H]
91- 95 F5.2 [-] [Zn/H] [-3.38/-0.28]? Zinc to Hydrogen abundance (G1)
97-100 F4.2 [-] e_[Zn/H] [0/0.18]? Uncertainty in [Zn/H]
--------------------------------------------------------------------------------
Global notes:
Note (G1): The abundance ratios [X/H] are calculated relative to the solar
abundances presented by Asplund et al. (2009ARA&A..47..481A 2009ARA&A..47..481A).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 26-Nov-2021